In spite of the high incidence of high-grade squamous intraepithelial lesions (SIL) (CIN II and CIN III) of the cervix among minorities in the U.S., and the importance of SIL in the natural history of cervical cancer. few risk factors for this disease have been identified. The objective of this multiethnic, matched case-control study is to more fully examine the associations of dietary and serum nutrient levels, human papillomavirus, and tobacco smoking on the risk for high-grade SIL. Subjects will be identified in two clinics on Oahu during the 5-year period 1992 to 1995. Cases will include 600 women with histologically- confirmed, high-grade SIL from any of the following ethnic groups: Hawaiian, Japanese, Chinese, Filipino, and Caucasian. Eligible controls will be women with negative pap smears. One control will be matched to each case on age (plus-or-minus 5 years) ethnicity, and clinic. A personal interview will include the following content areas: demographic information, diet history, reproductive and sexual history, hormone use, medical history, lifetime history of tobacco use, environmental tobacco smoke exposure, personal hygiene, and physical activity. A fasting blood specimen will be obtained to determine plasma erythrocyte levels of retinol, retinol esters, alpha- and gamma- tocopherol, alpha- and beta-carotene, lycopene, canthaxanthin, beta- crytoxanthin, lutein, folate, ascorbic acid, cholesterol, and cotinine, the presence of papillomavirus subtypes will be determined in exfoliated cell samples. Data analysis will examine the independent associations and interactive effects of dietary and biochemical measures of nutritional status, papillomavirus, tobacco smoke exposure, and other variables on the risk for high-grade SIL, using multiple conditional logistic regression. The study sample will provide sufficient statistical power to detect relatively weak exposure-disease relationships. This multiethnic, interdisciplinary study should contribute to an understanding of the epidemiology of high-grade SIL, particularly the role of dietary factors in its etiology. Given the well-recognized continuum of disease from dysplasia to carcinoma in situ to invasive cancer, this study will allow for the identification of risk factors for early lesions of the cervix which are potentially reversible. The findings should be especially pertinent to future efforts to control cervical disease among Native Hawaiians and other minorities, since dietary and infectious factors are amenable to modification.